FOLH1 and posterior cortical atrophy: Furthermore, even in our relatively large cohort consisting of 62 RPEs, the number of cases with a high ratio of negative PSMA areas was limited (15 cases PSMA%neg ≥ 20% and 6 cases with PSMA%neg ≥ 50%) due to the known natural low frequency of PSMA-negative tumours, of around 10% of all PCa.